Apparatus for electric smelting.



P. OREELMAN. I APPARATUS FORELEOTRIG SMELTING.

APPLICATION FILED JAN.7. 1904.

Patented Dec. 13, 1910.

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VQBJESSES:

F. OREELMAN. APPARATUS FOR ELECTRIC SMBLTING.

APPIiIGATION FILED'YJANJ. 1904.

Patented Dec. 13, 1910.

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INVENTOR:

WITNESSES:

, new and useful Improvements in Appara UNITED STATES PATENT OFFICE.

FRANK CREELMAN, OF NEW" YORK N. 'Y., ASSIGNQR TO THE WILLSON CARBLDE W ORKS COMPANY OF ST. CATHARINES, POBATION.

LIMITED, or sr. cnrnnnmns, CANADA, Acon- APPARATUS FOR ELECTRIC SIVIEL'IING.

Application filed January 7 To all whom it may concern:

Be it known that I, FRANK. Grumman, a citizen of the United States. residing in the borough of Manhattan, city, county, and State of New York, have invented certain tus for Electric Smelting, of which the following is a specification.

My invention aims to provide certain improvements especially applicable to electric furnaces for the manufacture of calcium carbid or similar products.

An important feature of theinvention is the supplying of a current of constant ampe'rage to the furnace, so that under sudden 'reductions in the internal resistance of the furnace, there can be no dangerous rise in .the quantity of current supplied; and thecontrolling of the operation of the furnace by means of variations in voltage. The op eration of the furnace is controlled by a regulator of any suitable sort which either moves the zone of fusion, or moves the material so as to gradually reduce all or a desired part of the material. The application of a constantcurrent, maintained constant by means outside of the furnace, is of special usefulness in connection with a regulator for automatically controlling the operation of the furnace. Tritling variations in the .ggte of movement of the electrode or of the aterial, which might produce a temporary reduction of the internal resistance, serve Such a constant current transformer would then serve the three purposes of reducing the voltage below that of the line,-maintaining the volume of current constant, and governing the regulator which controls the rate of operation of the furnace.

The electrical system and mechanism referred to are of special value in connection Specification of Letters Patent.

Patented Dec. 13, 1910.

, 1904:. Serial No. 188,038.

with a particular style of furnace wherein the entire material passes through anopening in which is maintained the zone of fusion, and from which the fused material runs into a receptacle beneath.

Various other improvements are referred to hereinafter.

The accompanying drawings illustrate certain embodiments of the invention.

Figure 1 is a longitudinal section through a furnace showing in side elevation a regulator controlling the rate of operation of the furnace; Fig. 2- is a plan of the regulator; F ig. 3 is a view of a part of the regulator similar to Fig. 1, but showing the parts in a different position; Fig. 4 is a section of the furnace at right angles to that shown in Fig. 1; Fig. 5 is aview similar to Fig. 1, showing the invention appliedto an ordi nary pot furnace, and showing a slightly different style of regulator; Fig' 6 is a diagrammatic view partly in section showing a hydraulic regulator applicable to either style of furnace; Fi 7 is a diagrammatic view of the electrical elements and connections for a group of three furnaces; Fig. 8 is a diagrammatic view of a transformer adapted for use as a part of my invention.

Referring to the embodiments illustrated, A represents as a whole an electric furnace, which according to my broad invention may be of any suitable construction, thecurrent to which is brought through leads B B from a constant current transformer C. The

wires running from the transformer to the line are indicated at D D. The specific construction of the transformer constitutes no part of this invention. Any suitable apparatus may be used. In fact a constant curconstruction, three different types being shown.

Referring now especially to Figs. 1 and '4, a furnace 1s illustrated having at its lower end an opening through which the material sion extends throughout the cross-section of the opening, thus insuring the fusion and reduction of all the material which passes through the furnace. The electrodes may be adjustable to compensate for the burnin; or wearing off of theirends. They are preferably fixed in operation. The walls of the furnace, the inlet for material, and the outlet for the gases generated, may be of the ordinary form shown or of any other suitable form. Such a furnace eliminates two serious defects of the furnaces now ordinarily used for the manufacture of calcium carbid. in the old type of furnaces, the fused or reduced material formed with a surrounding hard crust of only partially reduced material, which is surrounded in turn by a ccrta in amount of practically unaltered material. The crust is not only practially worthless as carbid, but its removal fromthe inclcsed pig of pure carbid is a cause of great expense, and dump heaps of it are of OlijQCilODtiblL odor. The old ui'n'educed material is gcnerall re-used, but the extra hamilling of it. especially in the red hot condition in which it is taken out of the furnace, is a matter of great difficulty and expense. The present furnace by reducing 7 completely all the material whichpasscs through it, saves a very large part of the eX- pense of manufacture of calcium carbid and similar products.

The finished product is carried away by a m'mveycr consisting preferably of a horizontal (or it may be sloping) line of separate trough-sections J which receive the fused material, and in which the material solidifies into a pig or pigs of suitable shape. This horizontal -':onveyer constitutes practicall a part of the furnace, serving to hold up the pool of fused material, and serving by its rate of movement to determine the ate of passage of the material tl'irough the zone of fusion. These trouglrsections travel on a series of itionary rollers K, or on any other suitable guide, and the line is maintained by introducing a new section at the starting end at proper intervals. A plate L depends from one side of the furnace, filling the internal space of the trough and substantially preventing access of air and burning away of electrodes, and also preventing escape of material or gases at this end. The plate L may be removable or may have a window therein, for permitting inspection of the conditions within the furnace. The other end of the trough is closed by means of the solid pig M of the product. The sections J may be of iron lined with slabs N of carbon or other suitable i'naterial to withstand the action of the great heat, and may overlap each other at. the ends as shown in Fig. l, or otherwise make a close joint and prevent the escape of any material. The trough is pushed gradually forward from the rear end in the direction of the arrow, the pig being broken and taken out of each section a l ter it has passed through the furnace, and a new section being added at the -rear end of the line as often as the line advances the length of one section. The regulator, there fore, in order to determine the rate of operation of this furnace, acts upon the line of trouglnsections J.

In Figs. 1, 2 and 3, I have shown a rcgw later the principles of which are well known, especially modified to adapt it to the moving of the line of trougl1-sections J. A continuously driven shaft 0 carries an eccentric which reciprocates a link P and oscillates a frame Q carrying pawls R R at opposite ends. These pawls by the engagement of i one or the other with a toothed wheel S, ro-

tate the wheel in one or the other direction, and through the inter-mediation of bevel gears T and U rotate a worm-shaft V, the motion of which is transmitted in turn to a pinion W, which reciprocates a pusher X having at its end a cross arm Y which bears against the rearmost of the sections J. The pawl R which effects a gradual withdrawal of the pusher X may be ()Fltttftl with the style of furnace here shown, the withdrawal of the pusher being effected quickly by lifting the rear end of the pusher X in the manner illustrated in Fig. 3 until its teeth are freed from those of the pinion \V, when it may be (prickly drawn bacluvard its full length and a new section introduced between the last section of the line and the cross bar Y at the end of the pusher. The pusher will then be dropped again, to come into ei'igagement with the pinion \V, and the pusher X will be quickly advanced by means of a hand wheel Z on the shaft V to bring the new section to bear hard up against the last previous section. The automatic operation then continues. For permitting the described movement of the pusher X, it may bemountcd in a frame (6 pivoted at I). The automatic regulation of the feed is ell'ectcd by means of a shield c loosely mounted on the shaft (Z and rovided with an arm (2 which is connectecl by a link f to the usual weighted arm E,or other movable member of the transformer or of any other suitable constant current regulator. As the arm E moves down in accordance with the falling resistance due to the accumulation of fused material, the shield c swings to the right. uncovering the pawl R. which gradually pushes the sections forward until normal conditions are established and the arm E returns to its normal position. There will ordinarily be no occasion for retarding the rate of operation of the furnace, but this may be accomplished if de ired by connecting the sections J to each other. and by connecting the bar X to the rear section. Upon the operation becoming too rapid, the pawl R will then come into action by the appropriate movement of the shield c, and the trough will be drawn backward.

The furnace of Fig. 5 is an ordinary pot or crucible furnace in which the operation proceeds by the gradual lifting of the upper electrode 9 as the fused product in the center of the mass of material rises. The raising and lowering of the electrode g is accomplished by means of a chain It. passing around a sprocket wheel j and carrying at its end a counterweight 7r. The drum j is turned in one direction or the other .by means of a worm shaft V driven as in Fig. 1 by means of a continuously rotating shaftO, link P, oscillating frame Q, pawls R R, toothed wheel S. and bevel gears T and U. The pawls may be controlled mechanically, as in Fig. 1, or they may be controlled by means of magnets Z controlled in turn by a double snap-switch m, the operating arm n of which is moved by means of a slide 0 connected to the arm E of the transformer or current regulator C. The furnace regulator here described could obviously be applied as well to the furnace of Fig. 1 as to that of Fig. 5..

A hydraulic governor is illustrated in Fig. 6 in a form especially applicable to the feeding movement of the furnace of Fig. 1. The pusher X is in the form of a ram or plunger working in a cylinder 7) and having a. head 9. The annular space in front of the head is constantly connected to'the pressure supply by means of a. pipe 7*, and this pipe has a branch 8 through which water may be supplied to the opposite or back end of the piston head 1 to force the ram forward by reason of the difi'erence in total pressure on the two sides of the head, due to the difference in area. The controlli g of'the forward movement is effected b a needle valve 1- carrying at its end a pinion u engaging a rack a connected to the movable member E of the current regulator. Between the valve t and the cylinder 7) a three-way cock w is interposed which connects the needle valve with the cylinder during the gradual forward movement of the pusher. and which connects the real-end of the cylinder with the waste pipe or to permit a quick return of the pusher by means of the pressure in the annular space in front of the piston, when a new section of the conveyer is to be added.

A. valve 3 is provided in a by-pass for moving the pusher quickly forward to take up the slack necessarily provided in the introduction of a new section.

The arrangement of the circuits by which the constant current is obtained is capable of considerable variation. A suitable and preferred arrangement is shown in Fig. 7, in which three furnaces represented at A receive electrical energy from main wires a Z), which in turn are supplied from an alternating current generator 0. Tlfe furnace typified at A may be supposed to represent the furnace of Fig. 1, having the central carbon pencil H and the lower carbon G. Or it may be an ordinary pot or crucible furnace. or any other suitable type of furnace. For each furnace A is provided a separate transformer C. the primary coilof which is connected with the wires D D. which are connected in multiple with the main circuit leads a b. The secondary coil of the transformer is connected with the wires B B constituting the local circuit for each furnace. A constant current for each single furnace may of course be obtained directly from a suitably wound dynamo; but assuming that the dynamo shown maintains a normal constantpotential or electromotive force upon the main wires. then the transformer C isof a type adapted to maintain a constant current in the circuit B B of its secondary coil, and which leads to the furnace. In fact in place of the single element C which both transforms the voltage and maintains a constant current. I may substitute a transformer which does. not maintain a constant current, and add also a current regulator of any suitable type which shall maintain the desired constant current. A suitable type of constant current transformer is shown in Fig. 8 diagram- .matically. The secondary coils d are fixed at opposite ends of the core which carries the magnetic circuit, while the primary coils e are made movable along the core and are counterbalanced by a series of levers. of

which only one is shown'at f, the projecting end E of which is utilized in governing the regulator as hereinbefore described. An increase in the current passing through the fixed secondary coils, causes the adjacent movable primary coils to recede therefrom and thereby diminishes the induction in such proportion as to maintain a constant cur-- rent. Whenever from any cause the resistance in its furnace falls, the transformer by proportionally reducing the voltage in the circuit of its secondary coil, maintains the current constant and prevents any rise or rush of current as would otherwise occur. Thus lnstead of a dangerous rise of current conditions or the current demands of the other furnaces.

In previous ingot furnaces the lime and "arbon had to be very finely ground so that the molten lime should not percolate too freely into the material outside of the Zone of fusion and thus form a pig of irregular quality and with a thick crust. \Vith my improved apparatus in which all the material passes through the zone of fusion and is reduced therein, the former expense for line grinding is not necessary. Also in previous ingot furnaces it has been found impracticable to use limestone, the crust formed in such a case being very hard as compared with that obtained by the use of lime. lVith my improved apparatus producing a crustless pig, limestone may be substituted for lime with a considerable saving in expense.

A SlllilClQIltlV Constant amperage for practical purposes may be obtained by other an rangements than that shown. For example a plant of several furnaces may be supplied from a constant potential generator, and ordinary transformers arranged .ith their several primary coils in seric ,1 the main circuit and their secondary coils connected one to each of the furnaces. A short circuit in one such furnace would not short-circuit the system and the abnormal quantity of current would be in inverse ratio to the number of furnaces. Therefore with any considerable number of furnaces the dist-urbance of normal conditions would be v light. The regulation for each furnace could be. accomplished separately by a volt meter, or automatically by a coil connected between the furnace terminals.

hat I claim is:-

1. In an electric. furnace. in combination, a pair of stationary electrodes arranged to permit the passage of the material between them from above. with an outlet opening directly beneath them and a transversely movable receptacle for the molten product arranged close beneath said electrodes, and beneath said opening. whereby theproduct in said receptacle sen es to supportthe material undergoing reduction in said opening.

2. In an electric furnace in eon'ibination, a pair of stationary electrodes arranged to permit the passage of the material between' them from above with an outlet opening directly beneath them, and a receptacle for the molten material comprising a series of conveyor sections adapted to pass succesvsivcly below said electrodes close beneath said opening to form a continuous pig of product and arranged close beneath the zone of fusion, whereby the product in said ret-q'itacle immediately. beneath the electrodes is molten and serves to support the material undergoing reduction.

3. In an electric furnace in combination means for fusing the material, a transversely movable receptacle receiving the fused 'product, and an actuating mechanism for said receptacle controlled by the variations in the voltage.

l. in coinbimltion, an electric arc furnace,

and means for sumalying thereto a current of constant amperage notwithstaiuling variations in the internal resistance of the fur nace, said furnace having an opening and constructed to maintain fusion of the material in said opening, and to withdraw the product therefrom progressively as it is formed and at a rate controlled by the variations in the voltage.

5. A regulating mechanism for electric furnaces comprising in combination a movable part of the furnace. a pusher therefor, and means for advancing said pusher by short steps-continuously in one direction, said pusher being adapted to be quickly ieturned to its starting point.

(3. An electric furnace, comprising a smelting chamber having a discharge 0 ening, and a receptacle movable across sai opening and arranged to retain a molten body within said chamber.

7. An electric furnace, comprising a smelt! ing chamber having a discharge opening, anr plurality of receptacles movable across said opening and arranger-l to retain a molten body within said chamber.

8. An electric furnace, comprising a smel ing chamber having a discharge opening, and a plurality of abutting receptacles movable across said opcnin and arranged to retain a molten body within said chamber.

9. An electric furnace, comprising a smelting chamber, having an open bottom, and a receptacle movable transversely beneath said botton'i and arranged to retain a molten body within said chamber.

10. in smelting chamber having an open bottom, and a plurality of rcceptadcs movable transversely b neath said bottom and arranged to retain a molten body within said chamber.

11. An electric furnace, comprising a smelting chamber havingan open bottom, and a plurality of abutting receptacles niovable transversely beneath said bottom and arranged to retain a molten body within said chamber.

electric furnace. comprising a 12. An electric furnace, comprising a smelting chamber having an open bottom, electrodes extending into said chamber, and a receptacle movable transversely beneath said bottom and arranged to retain a molten body within said chamber.

13. An electric furnace, comprising a. smelting chamber having an open bottom, electrodes extending into said chamber, and a. plurality of receptacles movable trans versely beneath said bottom and arranged to retain av molten body within said chamber. 1-1. An electric furnace, comprising a smelting chamber having an open bottom, electrodes extending into said chamber, and a plurality of abutting receptacles movable transversely beneath said bottom and ar ranged to retain a molten body within said chamber.

15. An electric furnace provided with electric heating means and having a traveling-receiver or hearth adapted to travel substantially horizontally through said furnace below said heating means for receiving the reduced material or product and conveyin the same from the furnace, the said traveling receiver or hearth being composed of detachable sections adapted to be transposed from end to end to permit of the same being made practically continuous in its travel through the furnace, and means for operat ing said receiver or hearth, substantially as and for the purpose set forth.

16. An electric furnace provided with electrical heating means and having a traveling receiver or hearth adapted to travel substantially horizontally through said furnace below said heating means for receiving the reduced material or product. and conveying the same from the furnace, the said traveling receiver or hearth being composed of detachable sections adapted. to be coupled and uncoupled to permit of the saniebeing made practically continuous in its travel through the furnace and being practically sealed at the points where it enters and leaves the furnace, respectively, and means for operating said receiver or hearth, substantially as and for the purpose set forth.

17. An electric furnace provided with electrical heating means and having a horizontally traveling recessed or troughshaped receiver or hearth. adapted to travel through said furnace below said heating means for receiving the reduced material or product and conveying the same from the furnace, and means for operating said re ceivcr or hearth, substantially as and for the purpose set forth.

18. An electric furnace provided with electrical heating means and liaving a traveling recessed or trough-shaped receiver or hearth adapted to travel substantially hori' Zontally through said furnace below said heating means for receiving the reduced material or product and conveying the same from the furnace, the said traveling receiver ing said receiver or hearth, substantially as and for the purpose set forth.

19. An electric furnace providedv with electrical heating means and having a trav cling recessed or trouglrshaped receiver or hearth adapted to travel substantially horizontally through said furnace below said heating means for receiving the reduced material or product and conveying the same from the furnace, the said traveling receiver or hearth being composed of detachable sections adapted to be transposed from end to end to permit of the same being made practically continuous in its travel through the furnace and being practically sealed at the points where it enters and leaves the furnace, respectively, and means for operating said receiver or hearth, substantially as and for the purpose set forth.

20. An electric furnace provided with electrical heating means and having a. travcling recessed or trough-shaped receiver or hearth adapted to travel below said heating means for receivingthe material andconveying therefrom the reduced material, the said receiver or hearth constituting the bottom and also a substantial portion of the sides of said furnace, and means for operating said receiver or hearth, substantially as and for the purpose set forth.

:21. An electric furnace provided with electrical heating means and having a traveling recessed or trough-shaped receiver or hearth adapted to travel below said heating means andhaving such depth thereto as to constitute the bottom of the furnace and the opposite sides thereof, such sides extending up to or near the level of the fusing Zone,

and means for operating said receiver or hearth, substantiallyas and for the purpose set forth. r

22. An electric furnace provided with electrical heating means andhaving a traveling receiver or hearth adapted to travel through said furnace below said heating means and being composed of detachable sections adapted to be tansposed from end to end to permit of said receiver being practically continuous in its travel through the furnace, driving connections engaging the two opposite sides of said traveling receiver or hearth, and means for actuating the said driving connections, sul'istantially as and for the purpose set forth. I,

23 Aniclectric furnace having a fusing or smelting chamber provided with means discharge opening and adapted to retain the charge Within said chamber.

In Witness whereof, I have hereunto signed my name in the presence of two subscribing Witnesses.

FRANK CREELMAN.

Witnesses Y Doamwo A. Usma, FRED WHITE. 

